I have a 480-487 lift comp cam in my 305 TBI. This lift really wrecked havoc with my vaccum and braking. I originally thought the issue was the brakes themselves and not the vaccum so I took it to a shop and had them checked out.. The guy there told me that it was my vaccum and I needed a pump he said not even to bother with a canister.

I'm kinda hesitant to buy the pump b/c they're upwards of 300 bucks so my question to you guys... I'm sure I'm not the only guy whose had this problem. Anyone have any luck with the vaccum canisters to fix vaccam loss through high cam lift? This is the route I'd love to go as they're less then 100 bucks in most cases. Any recomendations on brands, models if one would work?

If a pump is the way to go I will definitely man up and shell out the money. any experiences, word of mouth referennces on models, brands there?

Thanks!

 

I'd put a vacuum guage on it first to check it. You might be able to rent one from AutoZone. 480 lift doesn't sound that big to me. I'm running 600+ and I used a CompCams canister with disc brakes. I didn't bother even trying it without.

 

Hmm, interesting. I know my lift isn't that drastic compared to most cams, but I just thought though not drastic in a 350 or a bigger cubed engine it was drastic enough in the 305 to cause issues. I don't really know what else it could be though cos I have a brand new master cylinder, new rear drums and new front rotor and brake pads...

Good to know though a canister is an adequate solution for your big cam. That gives me hope : |)

 

Maybe a 305 makes some difference. I'd still go see if you could rent a guage from AutoZone. That would at least let you know if you have a vacuum leak somewhere.

 

OK I will do this. And I was looking at the Comp Cams Canisters and they look really good and only cost 60 bucks. Much better then 300 : )

 

Yep biggest pain is finding a place to mount them. Thinking more about it now I think I just used the Jegs one since it had a guage on it too. The bracket didn't look like the compcams one but they might have changed them I bought mine many years ago. It has a guage on the top which is kinda useless most of the time unless you just need to spot check it sometime for a leak.

 

That a pretty big cam for the 305. Whats the LSA? Its not the lift that causes vacuum problems its the lobe duration and overlap.

You can also lash your lifters a few thousandths of an inch and it will act as the cam has less duration

I have a similar grind in my 350 just slightly more lift and 108lsa and I lost some feel to the pedal and I don't have as many pumps as I used to but its not like I couldn't drive. I had to re tune my carb for max vac as well. Get a canister, It doesn't hurt. You could remote mount them under the dash, or you can use an electric vacuum pump which can also be remotely mounted. IMO I don't like the sound of the electric pumps.

 

I used an SSBC pump kit and a vacuum can. If it were my car, the can probably would have been OK for me. The can will only store vacuum at the highest point the engine will make. So if normal idle you dont have enough vacuum for proper braking but at say some point during it running/driving, the engine hits 15-16" of vacuum, the can will store that. Only bad part is repeated braking. Usually two or so stops right after another depletes the can and the pedal will get hard again.

With the SSBC kit it had great brakes but had two problems. First, the pump would run every time I hit the brakes, second it run intermittenly for no reason. I put the vacuum can back in to give it extra vacuum storage so the pump wouldnt have run every time the brakes were applied. The second running problem i found was with the design of the kit. It put the vacuum switch inline with the pump and power booster. Problem was the line itself doesnt hold vacuum against the pump so as soon as the pump stopped running, vacuum in the line would drop and kick the pump on again, even though it vacuum was stored in the booster fine. What I did was put the SSBC vacuum switch in the threaded port of the vacuum canister and made sure the canister was grounded (vacuum switch has to complete the ground circuit for the pump to run) and problem solved.

Anyway, your not running too big of a cam so try a canister first, might work great

 

Ive got a 385 with a tight lsa and I only pull 9" of vacuum at idle in gear.... the vacuum canister helps alot. You will definetely adjust your driving style to be more effecient when pumping the brakes makes em a little softer with each pump. Whats your lsa and did you degree your cam?